Polyurethane foams are widely known and used in automotive, housing and other industries. Foam is generally referred to as rigid, microcellular, or flexible. Typically, in the preparation of polyurethane foams, a tertiary amine catalyst is used to accelerate the reaction of the polyisocyanate with water to generate carbon dioxide as a blowing agent and to accelerate the reaction of polyols to promote gelling of the reaction. Tertiary amines generally are malodorous and offensive and many have high volatility due to low molecular weight.
Representative patents showing the use of various tertiary amines for polyurethane foams are as follows:
U.S. Pat. No. 2,941,967 discloses tertiary amine catalytic systems containing aliphatically bound ether oxygen atoms having singular and bis functional tertiary amine units. Representative tertiary amines include dimethyl-(2-methoxy-ethyl)amine and 1,4-bis-(3'-dimethylaminopropoxy) butane.
U.S. Pat. No. 4,186,254 discloses alkoxylated derivatives of tertiary amines represented by the formula: ##STR1## wherein R and R.sub.1 are lower alkyl and x is 0-2. formed by condensing an alkoxy amine with formaldehyde and a lower alkanol and then hydrogenating the resultant product. Representative alkoxylated amines include methoxyethoxypropylamine.
U.S. Pat. No. 4,122,038 discloses the manufacture of polyurethane foams using a catalyst represented by the formula: ##STR2## wherein R are lower alkyl which are formed by reacting an alkanolamine with an alkylene oxide as, for example, dimethylethanolamine with ethylene oxide to produce 2-(2-dimethylaminoethoxy) ethanol.
U.S. Pat. No. 4,510,269 discloses tertiary amine catalyst systems which are poly(dialkylaminoalkyl) ethers. These are represented by the general formula: ##STR3## wherein R is lower alkyl and A is a straight chain hydrocarbon. Secondary amines or dialkylamino alcohols are reacted with epihalohydrins. The advantage of the catalyst systems is that they have low vapor pressure, minimal smell, chemically bond with the urethane during the reaction and do not impair the stability of the completed polyurethane part.
U.S. Pat. No. 4,350,778 discloses the preparation of tertiary amines containing secondary alcohol functionality by reacting bis-dimethylaminopropylamine with propylene oxide.
U.S. Pat. No. 4,590,223 discloses the preparation of tertiary amines containing secondary alcohols by reacting N-alkyl piperazines with an alkylene oxide.